Putting the change in climate change

A trio of papers in PNAS look at climate change, both past and present.

This week's PNAS sees a trio of papers that all touch on one of the big science issues of our time: climate change. Although there still remain some pockets of skeptics and denialists, just about everyone else on the planet has looked at the data and come to the conclusion that our use of fossil fuels is having a profound effect on the climate.

A pair of papers both seek to understand the changes we are experiencing by examining past data. The first1 examines the rates of change of radiative forcing by looking at the changing concentrations of several greenhouse gases (CO2, N2O, CH4) over the past 20,000 years, along with proxy solar data. The results are pretty damning, with almost flat rates of change from 20,000 years ago until about 200 years ago. The end of this period coincides with the industrial revolution and our massive increase in fossil fuel consumption.

The second paper2 also looks at the past 20,000 years, but this time in the oceans, and at the effects of rapid climate change on deep-water ecosystems. Using fossilized ostracodes (a small bivalve that lives in deep sea communities along with copepods and nematodes), the authors show that rapid climate change in this ecosystem (caused by the ending of the ice age and the changes to ocean circulation that the sudden influx of cold, fresh water had) caused a widespread disruption of the local ecosystem that took over 4000 years to recover.

Although some level of climactic disturbance is now inevitable, most experts agree that there is still some time remaining to head off the worst, assuming that we as a species can implement a multilayered approach to the problem. Reduction of fossil fuel usage, along with a massive increase in renewable energy production is one step, as is carbon sequestration, most likely in the form of plant growth (this has the added benefit of increasing biodiversity, never a bad thing in and of itself).

The final paper3 looks at the role of Canada's managed forests as a carbon sink. At the time of the Kyoto Protocol, it was assumed that these large areas of forest would sequester carbon from the atmosphere, but new data shows that forest fires and insect outbreaks have meant that the forests have actually acted as a net carbon source. The authors make the point that future international agreements, such as those proposed at the Bali summit, will need to carefully take into account the realities of natural disturbances when it comes to evaluating roles of forests and other ecosystems in climate change mitigation.

If that all seems rather bleak, take heart in the fact that there is still time to act. To that end, watch this space for a future announcement on the subject.